Cicero's Topica is one of the canonical texts on ancient rhetorical theory. This is the first full-scale commentary on this work, and the first critical edition that is informed by a full analysis of its transmission. Cicero recommends an Aristotelian theory of argumentation to an expert onRoman law. The introduction and the commentary seek to elucidate the exact origins of the theory of argument used by Cicero and explain how it works. Moreover, since Cicero's suggestions for a reform of Roman civil law have parallels in similar efforts within the legal profession, Tobias Reinhardtconsiders how much common ground there is between Cicero and the jurists.